JP2007113295 discloses an air lift pump for excavating sediment and sludge that has deposited and hardened on a sub-aqueous bottom over a period of time. The pump has a riser pipe whose lower end header reaches as far as the sub-aqueous bottom; a nozzle which is enclosed by the header and sprays high-pressure fluid, and a blade for scraping material from the sub-aqueous bottom.
JP1207535 discloses an air lift pump for pumping mud from a water bottom such as a river bed.